Drawbench

ABSTRACT

A device and method for drawing tubes and rods wherein the workpiece is fixed within a hydraulic cylinder and the die, acting as a piston, is moved along the workpiece.

United States Patent Brak et al.

[15] 3,654,794 [4 1 Apr. 11, 1972 [54] DRAWBENCH [72] Inventors: Stephen B. Brak, Tinley Park; Clarence Steves, Hickory Hills, both of 111.; Ross M. Mayfield, deceased, late of Glen Ellyn, 11].,

by Georgia P. Mayfield, Sole Heir, of

[211 Appl. No.: 805,383

[56] References Cited UNITED STATES PATENTS 2,927,372 3/1960 Powell ..72/285 X 3,327,513 6/1967 Hinshaw ..72/274 X 3,449,935 6/l969 McAllen ..72/60 Primary Examiner -Charles W. Lanham Assistant Examiner-Michael J. Keenan An0rneyRoland A. Anderson [57] ABSTRACT- A device and method for drawing tubes and rods wherein the workpiece is fixed within a hydraulic cylinder and the die, act- [52] US. Cl as a piston is moved along the workpiec 511 Int. Cl ..B21c3/12 [58] Field of Search ..72/283, 285, 57, 274 6 Chums, 1 Drawms Figure 2/ f I? 1 m DRAWBENCi-i The invention described herein was made in the course of,

end of the tube is swaged over shoulder 36 of the mandrel.

The mandrel 33 and swaged tube 37 are then inserted through the die opening 20 and corresponding aperture 19 in piston 13. Knob 35 of mandrel 33 is forced through the beveled tongs or under, a contract with the United States Atomic Energy 5 27 into ipp 26 which maintains a locked Position Commission. due to spring 30. At this point, when the mandrel 33 is locked within gripping device 26 and the swaged portion of tube 37 is BACKGROUND OF THE INVENTION in contact with die opening 20, the hydraulic fluid is admitted A drawbench is a device used for reducing the diameter of lo g g g g z g gg gg s 233f; 2 I322? 21223?it;as.z srzzitzs..rlstsaiazi w; insure a tig t sea etween t e ie an piston an LLFEPEZZJTLiZQZ.31326553?33f? iii-2033335; j g gg m t g g 9 g g g g g may e rou e piston. at case, t e y rau 1c ui t workpiece through the fixed dies; while in other cases, hydraua 5 53;: 5 ;21 :1212; end cap 12 in order to gisg g are used to ram or Push the Workplece through the remain centered during the drawing operation. Unless the mandrel 33 is extremely long, it is not absolutely necessary for iiss g ggz fgz sgfi z frgi gz g s ig z a 20 it to be so centered. For workpieces of a few feet in length the drawiiench while the die mov s along the workpiece a device dFVlCedQf thls mYem-lon Self Cemermg that the movement can be constructed which is considerably lighter, smaller and g f iigg 3 221 235 3; gg??? figggg g ggz zggi gfig 2 2F 5: g ig g gi fggz gl i gii' 52 3232 5 may be 2 5 one direction only, then end cap 12 is not required for the sucy g cessful functlon of the invention. Some means of stopping BRIEF DESCRIPTION OF THE DRAWING piston 13 would be required if end cap 12 were removed but that is all that would be required, because any oil leakage The single FIGURE is a view partially in cross section of the could i l run t f h d 1 device Ofthls lnvemlon- 30 Several experiments have been performed on both copper and stainless steel tubes. It was found that copper tubes could DESCRlPTION OF THE PREFERRED EMBODIMENT be drawn with a pressure of about 100 psi. on a piston head As shown in the Figure the device consists of a hydraulic of 8 square inches and stainless steel tubes could be drawn cylinder 10 closed at either end by caps 11 and 12. A piston 13 with a pressu e of about 300 p.s.i. on the same piston head. is sealed within cylinder 10 by two O-rings 14 in peripheral 35 Thefollowlng table sets out the aforementioned experiments.

TABLE Start Finish Tube Outside Inside Tube Outside Inside Experiment length diameter diameter length diameter diameter Copper Stainless steel grooves 15. A cylindrical die 16 is housed within the side of piston 13 which faces away from end cap 11 and is sealed to the piston by O-ring 17 in an internal groove 18 in the piston. A centrally located aperture 19 in piston 13 is aligned with a centrally located opening 20 in die 16.

End cap 11 is pivotally connected at one end of flange 21 by hinge 22 and is connected to the other end of the flange by bolt 23. End cap 11 has a hydraulic fluid inlet 24 in communication with cylinder 10 via a chamber 25 in the end cap. A gripping device 26 housed within chamber 25 consists of two hinged tongs 27 mounted on frame 28. The tongs 27 whichhave beveled surfaces 29 are urged together by spring 30. Frame 28 is sealed within end cap 11 by O-ring 31, and the end cap is sealed with cylinder 10 by O-ring 32.

A mandrel 33 has a reduced diameter portion 34 and a knob 35. A shoulder 36 acts as a transition between the reduced diameter portion 34 and the rest of the mandrel 33. A workpiece, shown in the drawing as tube 37, is swaged at one end over shoulder 36 of the mandrel 33. The other end of mandrel 33 rests in a hollow 38 in end cap 12. End cap 12 is connected at one end to flange 39 by hinge 40 and at the other end by 70 bolt 41. The end cap 12 has a hydraulic fluid outlet 42 in com-{ munication with cylinder 10.

Where the workpiece is a tube the device of this invention; may be operated as follows: The piston 13 is moved proximate:

- end cap 11. A mandrel 33 is placed within a tube 37 and one.

Although only tubes were reduced in the above experiments it is clear that the device is applicable to rods as well. Modification of gripping device 26 would be necessary if the rod did not have a knob at one end. Threading one end of the rod and adapting end cap 11 to receive the threaded end would be one simple solution to the problem. It should also be clear from the above description that more than one tube or rod can be reduced at one time provided that die 16 and gripping device 26 are designed to accommodate them.

When die 16 is carried in piston 13 as shown, no special connection between the piston and die is necessary because the force of the drawing operation maintains the seat between die and piston. If, however, die 16 were carried on the opposite side of piston 13, then the combined force from the workpiece being drawn and the pressure difi'erential on the die and piston due to the difference in areas exposed to the hydraulic fluid might cause the die and piston to separate. if the drawing operation is in only one direction then no problem is encountered because die 16 can always be carried on the leading face of piston 13. It is contemplated within the scope of this invention that upon the termination of one piston stroke, end cap 12 may be removed and a new die substituted for the old. Thereafter, end cap 12 is closed and hydraulic fluid is admitted to cylinder 10 through outlet port 42 until piston 13 moves down the cylinder to perform another drawing operation in the opposite direction. It is during this second drawing operation that set screws or the like are required to maintain the new die within piston 13. During the second or reverse stroke the fluid inlet 24 would act as an outlet for any fluid leaking through the piston 13 or die 16.

It is understood that the invention is not restricted to the embodiments disclosed herein but is defined by the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A drawbench comprising: a hydraulic cylinder, a piston movable within said cylinder, a die carried by the piston on the leading face thereof, means for supporting a stationary rigid workpiece within said cylinder in a position fixed with respect to the axis thereof, and mah'sY'Gr'EviBg'saiU piston the length of said cylinder along said workpiece to reduce the diameter of said workpiece.

2. The device of claim 1 wherein the workpiece is a tube; and further comprising a mandrel fixed in the cylinder, said 'tube positioned about and fixed with respect to the mandrel,

3. The device of claim 2 and further comprising means for maintaining the mandrel centered within the cylinder while the die is moved along the workpiece.

4. The device of claim 3 wherein the means for maintaining the mandrel centered within the cylinder comprises: an end cap for said cylinder containing a hollow situated in the center of the end cap and into which one end of the workpiece or mandrel is inserted.

5. A method of drawing a rod or tube comprising: supporting said rod or tube in a fixed position within a cylinder, maintaining said rod or tube stationary within said cylinder, and hydraulically moving a piston containing a die on its leading face along the length of said cylinder over said rod or tube to reduce the diameter thereof.

6. The method claim 5 wherein after the drawing operation a further drawing operation is performed by changing dies in the piston, draining hydraulic fluid from the cylinder, and admitting hydraulic fluid to the cylinder at the opposite end from the previous drawing operatic 

1. A drawbench comprising: a hydraulic cylinder, a piSton movable within said cylinder, a die carried by the piston on the leading face thereof, means for supporting a stationary rigid workpiece within said cylinder in a position fixed with respect to the axis thereof, and means for moving said piston the length of said cylinder along said workpiece to reduce the diameter of said workpiece.
 2. The device of claim 1 wherein the workpiece is a tube; and further comprising a mandrel fixed in the cylinder, said tube positioned about and fixed with respect to the mandrel.
 3. The device of claim 2 and further comprising means for maintaining the mandrel centered within the cylinder while the die is moved along the workpiece.
 4. The device of claim 3 wherein the means for maintaining the mandrel centered within the cylinder comprises: an end cap for said cylinder containing a hollow situated in the center of the end cap and into which one end of the workpiece or mandrel is inserted.
 5. A method of drawing a rod or tube comprising: supporting said rod or tube in a fixed position within a cylinder, maintaining said rod or tube stationary within said cylinder, and hydraulically moving a piston containing a die on its leading face along the length of said cylinder over said rod or tube to reduce the diameter thereof.
 6. The method claim 5 wherein after the drawing operation a further drawing operation is performed by changing dies in the piston, draining hydraulic fluid from the cylinder, and admitting hydraulic fluid to the cylinder at the opposite end from the previous drawing operation. 